Offline Triac Dimmable LED Driver Demonstration Board


ISL1903DEMO1Z demo board converts a low line AC input voltage (120V) to a 42V, 350mA constant current output to drive LEDs. It is implemented with Renesas' critical conduction mode (CrCM) single ended buck controller, the ISL1903. It demonstrates fundamental functions of the ISL1903, including soft-start, triac dimming, overvoltage protection, short circuit protection, etc. The circuit operates in CrCM with variable frequency and allows for near zero-voltage switching (ZVS). Typical efficiency is about 87% at full load. This application note covers the test setup, performance data, dimming data, schematics, layout and BOM.


  • Input voltage VIN: 96V to 144V
  • Output voltage VO: 28V to 42V
  • Output current IO: 350mA (14W)
  • Board dimensions: 55×26×15mm3 (L×W×H)
  • Input power factor greater than 0.95
  • Total harmonic distortion less than 15%
  • Peak efficiency at full load: 87%
  • 0-100% flicker free dimming with leading and trailing edge dimmers


  • Industrial and commercial LED lighting
  • Retrofit LED lamps with triac dimming
  • Universal AC mains input LED retrofit lamps
  • AC or DC input LED ballasts

ISL1903DEMO1Z Offline Triac Dimmable LED Driver Top of Evaluation Board

ISL1903DEMO1Z Top of Evaluation Board

ISL1903DEMO1Z Offline Triac Dimmable LED Driver Bottom of Evaluation Board

ISL1903DEMO1Z Bottom of Evaluation Board





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Disclaimer: THIS MATERIAL IS PROVIDED “AS-IS” FOR EVALUATION PURPOSES ONLY. RENESAS ELECTRONICS CORPORATION AND ITS SUBSIDIARIES (collectively, “Renesas”) DISCLAIM ALL WARRANTIES, INCLUDING WITHOUT LIMITATION, FITNESS FOR A PARTICULAR PURPOSE AND MERCHANTABILITY. Renesas provides evaluation platforms and design proposals to help our customers to develop products. However, factors beyond Renesas' control, including without limitation, component variations, temperature changes and PCB layout, could significantly affect the product performance. It is the user’s responsibility to verify the actual circuit performance.